Communications device, infrastructure equipment and methods

ABSTRACT

A communications device that, when in an inactive state, transmits a first signal comprising a random access preamble and a first portion of data to infrastructure equipment, receives a random access response message from the infrastructure equipment, and transmits a second signal comprising a second portion of the data to the infrastructure equipment.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.17/391,070, filed Aug. 2, 2021, which is a continuation of U.S.application Ser. No. 16/475,697, filed Jul. 3, 2019 (now U.S. Pat. No.11,102,821), which is based on PCT filing PCT/EP2018/050096, filed Jan.3, 2018, which claims priority to EP 17150480.6, filed Jan. 5, 2017, theentire contents of each are incorporated herein by reference.

BACKGROUND Field of Disclosure

The present disclosure relates to communications devices which areconfigured to transmit data to and receive data from infrastructureequipment of a wireless communications network, in accordance with anenhanced random access (RACH) procedure.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Third and fourth generation mobile telecommunication systems, such asthose based on the Third Generation Project Partnership (3GPP) definedUniversal Mobile Telecommunications Standard (UMTS) and Long TermEvolution (LTE) architecture are able to support more sophisticatedservices than simple voice and messaging services offered by previousgenerations of mobile telecommunication systems. For example, with theimproved radio interface and enhanced data rates provided by LTEsystems, a user is able to enjoy high data rate applications such asmobile video streaming and mobile video conferencing that wouldpreviously only have been available via a fixed line data connection.The demand to deploy third and fourth generation networks is thereforestrong and the coverage area of these networks, i.e. geographiclocations where access to the networks is possible, is expected toincrease rapidly. However, whilst fourth generation networks can supportcommunications at high data rate and low latencies from devices such assmart phones and tablet computers, it is expected that future wirelesscommunications networks, will be expected to efficiently supportcommunications with a much wider range of devices associated with awider range of data traffic profiles, for example including reducedcomplexity devices, machine type communication devices, high resolutionvideo displays and virtual reality headsets. Some of these differenttypes of devices may be deployed in very large numbers, for example lowcomplexity devices for supporting the “The Internet of Things”, and maytypically be associated with the transmissions of relatively smallamounts of data with relatively high latency tolerance, whereas othertypes of device, for example supporting high-definition video streaming,may be associated with transmissions of relatively large amounts of datawith relatively low latency tolerance.

There is therefore expected to be a desire for future wirelesscommunications networks, which may be referred to as 5G or new radioaccess technology (which may be denoted new RAT or, simply, NR)networks, to support efficiently connectivity for a wide range ofdevices associated with different applications with differentcharacteristic data traffic profiles, resulting in different deviceshaving different operating characteristics and/or requirements.

The introduction of new radio access technology (RAT) systems/networkstherefore gives rise to new opportunities as well as challenges. Onesuch challenge is how to employ random access (RACH) procedures (whichmay be used for initial access from an idle mode, handover, RRCconnection re-establishment, etc.) in NR systems more efficiently. Inparticular, there are no sufficient solutions or schemes at present forNR communications devices which can accommodate large data transmissionsusing RACH without those communications devices transition to aconnected state.

SUMMARY OF THE DISCLOSURE

The present disclosure can help address or mitigate at least some of theissues discussed above, and provide solutions for communications devicesto transmit large amounts of data using RACH without having totransition to a connected mode. As such, embodiments of the presenttechnique can provide A communications device for transmitting data toor receiving data from a wireless communications network comprisestransmitter circuitry configured to transmit signals to one or moreinfrastructure equipment of the wireless communications network via awireless access interface provided by the one or more infrastructureequipment, receiver circuitry configured to receive signals from one ormore of the infrastructure equipment via the wireless access interface,and controller circuitry configured to control the transmitter circuitryand the receiver circuitry to transmit or to receive the signalsrepresenting data. When the communications device is in an inactivestate, the controller circuitry is configured in combination with thereceiver circuitry and the transmitter circuitry to transmit a firstsignal comprising a random access preamble and a first portion of datato one of the infrastructure equipment, to receive a random accessresponse message from the infrastructure equipment, and to transmit asecond signal comprising a second portion of the data to theinfrastructure equipment.

Embodiments of the present technique, which further relate to aninfrastructure equipment, methods of operating a communications deviceand infrastructure equipment, as well as circuitry for the same, canprovide a hybrid, enhanced RACH procedure which can be used in NRwireless communications system which has both the advantage of thereduced delay performance of the presently known two-step RACHprocedure, whilst large amounts of data can be accommodated with thedata transmission with the RACH.

Respective aspects and features of the present disclosure are defined inthe appended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 is a schematic block diagram of a wireless communications systemwith architectural components corresponding to that of an exampleenhanced new radio or 5G network;

FIG. 2 is a schematic representation illustrating steps in a four-steprandom access procedure in a wireless telecommunications network;

FIG. 3 is a schematic representation illustrating an example of uplinkdata transmission of a communications device in RRC_INACTIVE mode with adownlink response from the network;

FIG. 4 is a schematic representation illustrating an example RACHprocedure which could be applied for transmissions of small amounts ofdata;

FIG. 5 is a schematic representation illustrating an example two-stepRACH procedure which could be applied for transmissions of small amountsof data;

FIG. 6 is a schematic representation illustrating steps in a two-steprandom access procedure in a wireless telecommunications network;

FIG. 7 is a part schematic representation, part message flow diagram ofcommunications between a communications device and an infrastructureequipment of a wireless communications network in accordance withembodiments of the present technique; and

FIG. 8 shows a flow diagram illustrating a process of communicationsbetween a communications device and an infrastructure equipment inaccordance with embodiments of the present technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

New Radio Access Technology (5G) As mentioned above, the embodiments ofthe present invention can find application with advanced wirelesscommunications systems such as those referred to as 5G or New Radio (NR)Access Technology. New Radio Access Technology (RAT) has been proposedin [1] to develop a new RAT for the next generation wirelesscommunication system, i.e. 5G, and in 3GPP a Study Item (SI) on NR hasbeen agreed [2] in order to study and develop the new RAT. The new RATis expected to operate in a large range of frequencies, from hundreds ofMHz to 100 GHz and it is expected to cover a broad range of use cases.The use cases that are considered under this SI include:

-   -   Enhanced Mobile Broadband (eMBB)    -   Massive Machine Type Communications (mMTC)    -   Ultra Reliable & Low Latency Communications (URLLC)

The aim of 5G is not only mobile connectivity for people, but to provideubiquitous connectivity for any type of device and any type ofapplication that would benefit from being connected. Many requirementsand use-cases are still being discussed, but amongst those are:

-   -   Low latency    -   High data rates    -   Millimetre wave spectrum use    -   High density of network nodes (e g small cell and relay nodes)    -   Large system capacity    -   Large numbers of devices (e.g. MTC devices/Internet of Things        devices)    -   High reliability (e.g. for vehicle safety applications, such as        self-driving cars)    -   Low device cost and energy consumption    -   Flexible spectrum usage    -   Flexible mobility

An example configuration of a wireless communications network which usessome of the terminology proposed for NR and 5G is shown in FIG. 1 . InFIG. 1 a plurality of transmission and reception points (TRP) 10 areconnected to distributed control units (DU) 11.1, 11.2 by a connectioninterface represented as a line 3. Each of the transmitter receiverpoints (TRP) 10 is arranged to transmit and receive signals via awireless access interface within a radio frequency bandwidth availableto the wireless communications network. Thus within a range forperforming radio communications via the wireless access interface, eachof the TRP 10, forms a cell of the wireless communications network asrepresented by a dashed line 8. As such wireless communications devices12 which are within a radio communications range provided by the cells10 can transmit and receive signals to and from the TRP 10 via thewireless access interface. Each of the distributed control units 11.1,11.2 are connected to a coordinating unit (CU) 14 via an interface 16.The CU 14 is then connected to the a core network 17 which may containall other functions required for communicating data to and from thewireless communications devices and the core network 17 may be connectedto other networks 18.

The elements of the wireless access network shown in FIG. 1 may operatein a similar way to corresponding elements of an LTE network well-knownand defined in the relevant standards administered by the 3GPP (RTM)body, and also described in many books on the subject, for example,Holma H. and Toskala A [3]. It will be appreciated that operationalaspects of the telecommunications network represented in FIG. 1 , and ofother networks discussed herein in accordance with embodiments of thedisclosure, which are not specifically described (for example inrelation to specific communication protocols and physical channels forcommunicating between different elements) may be implemented inaccordance with any known techniques, for example according to currentlyused approaches for implementing such operational aspects of wirelesstelecommunications systems, e.g. in accordance with the relevantstandards.

The transceiver processors TRP 10 of FIG. 1 may in part have acorresponding functionality to a base station or eNodeB of an LTEnetwork, and so the terms TRP and eNodeB in the following descriptionare interchangeable. Base stations, which are an example of radionetwork infrastructure equipment, may also be referred to as transceiverstations/NodeBs/eNodeBs (eNBs)/gNodeBs (gNBs), and so forth. Similarlythe communications devices 12 may have a functionality corresponding todevices know for operation with an LTE network and may also be referredto as mobile stations, user equipment (UE), user terminal, terminaldevice, mobile radio, communications device, and so forth. It will beappreciated therefore that operational aspects of a new RAT network (forexample in relation to specific communication protocols and physicalchannels for communicating between different elements) may be differentto those known from LTE or other known mobile telecommunicationsstandards. However, it will also be appreciated that each of the corenetwork component, base stations and terminal devices of a new RATnetwork will be functionally similar to, respectively, the core networkcomponent, base stations and terminal devices of an LTE wirelesscommunications network.

Current RACH Procedures in LTE

In wireless telecommunications networks, such as LTE type networks,there are different Radio Resource Control (RRC) modes for terminaldevices. For example, it is common to support an RRC idle mode(RRC_IDLE) and an RRC connected mode (RRC_CONNECTED). A terminal devicein the idle mode may transition to connected mode, for example becauseit needs to transmit uplink data or respond to a paging request, byundertaking a random access procedure. The random access procedureinvolves the terminal device transmitting a preamble on a physicalrandom access channel and so the procedure is commonly referred to as aRACH or PRACH procedure/process.

In addition to a terminal device deciding itself to initiate a randomaccess procedure to connect to the network, it is also possible for thenetwork, e.g. a base station, to instruct a terminal device in connectedmode to initiate a random access procedure by transmitting to theterminal device an instruction to do so. Such an instruction issometimes referred to as a PDCCH order (Physical Downlink ControlChannel order), see, for example, Section 5.3.3.1.3 in ETSI TS 136 213V13.0.0 (2016-01)/3GPP TS 36.212 version 13.0.0 Release 13 [4].

There are various scenarios in which a network triggered RACH procedure(PDCCH order) may arise. For example:

-   -   a terminal device may receive a PDCCH order to transmit on PRACH        as part of a handover procedure    -   a terminal device that is RRC connected to a base station but        has not exchanged data with the base station for a relatively        long time may receive a PDCCH order to cause the terminal device        to transmit a PRACH preamble so that it can be re-synchronised        to the network and allow the base station to correct timings for        the terminal device    -   a terminal device may receive a PDCCH order so that it can        establish a different RRC configuration in the subsequent RACH        procedure, this may apply, for example, for a narrowband IoT        terminal device which is prevented from RRC reconfiguration in        connected mode whereby sending the terminal device to idle mode        through a PDCCH order allows the terminal device to be        configured in the subsequent PRACH procedure, for example to        configure the terminal device for a different coverage        enhancement level (e.g. more or fewer repetitions)

For convenience, the term PDCCH order is used herein to refer tosignalling transmitted by a base station to instruct a terminal deviceto initiate a PRACH procedure regardless of the cause. However, it willbe appreciated such an instruction may in some cases be transmitted onother channels/in higher layers. For example, in respect of anintra-system handover procedure, what is referred to here as a PDCCHorder may be an RRC Connection Reconfiguration instruction transmittedon a downlink shared channel/PDSCH.

When a PDCCH order is transmitted to a terminal device, the terminaldevice is assigned a PRACH preamble signature sequence to use for thesubsequent PRACH procedure. This is different from a terminal devicetriggered PRACH procedure in which the terminal device selects apreamble from a predefined set and so could by coincidence select thesame preamble as another terminal device performing a PRACH procedure atthe same time, giving rise to potential contention. Consequently, forPRACH procedures initiated by a PDCCH order there is no contention withother terminal devices undertaking PRACH procedures at the same timebecause the PRACH preamble for the PDCCH ordered terminal device isscheduled by the network/base station.

FIG. 2 shows a typical RACH procedure used in LTE systems which could beapplied to an NR wireless communications system such as that describedby FIG. 1 . A UE 12, which could be in an inactive or idle mode, mayhave some data which it needs to send to the network. To do so, it sendsa random access preamble 20 to a gNB 10. This random access preamble 20indicates the identity of the UE 12 to the gNB 10, such that the gNB 10can address the UE 10 during later stages of the RACH procedure.Assuming the random access preamble 20 is successfully received by thegNB 10 (and if not, the UE 12 will simply re-transmit it with a higherpower), the gNB will transmit a random access response 22 message to theUE 12 based on the identity indicated in the received random accesspreamble 20. The random access response 22 message carries a furtheridentity which is assigned by the gNB 10 to identify the UE 12, as wellas a timing advance value (such that the UE 12 can change its timing tocompensate for the round trip delay caused by its distance from the gNB10) and grant uplink resources for the UE 12 to transmit the data in.Following the reception of the random access response message 22, the UE12 transmits the scheduled transmission of data 24 to the gNB 10, usingthe identity assigned to it in the random access response message 22.Assuming there are no collisions with other UEs, which may occur ifanother UE and the UE 12 send the same random access preamble 20 to thegNB 10 at the same time and using the same frequency resources, thescheduled transmission of data 24 is successfully received by the gNB10. The gNB 10 will respond to the scheduled transmission 24 with acontention resolution message 26.

In various 3GPP RAN2 meetings, some agreements have been achieved onassumptions for how UE states (e.g. RRC_IDLE, RRC_CONNECTED etc.) maytranslate to NR systems. In RAN2 #94, it was agreed that a new“inactive” state should be introduced, where the UE should be able tostart data transfer with a low delay (as required by RAN requirements).At the time of RAN2 #94, an issue concerning how data transmissionswould work when UEs are in the inactive state were unresolved; it wasagreed that it was for further study whether data transfer shouldachieved by leaving the inactive state or whether data transfer shouldoccur from within the inactive state.

In RAN2 #95, it was agreed that the possibility of the UE being able totransmit data in the inactive state without transition to connectedstate will be studied.

In RAN2 #95bis, two approaches were identified as follows, in additionto a baseline move to the connected state before the transmission ofdata:

-   -   Data could be transmitted together with an initial RRC message        requesting a transition to the connected state, or    -   Data could be transmitted in a new state.

In RAN2 #96, two email discussions are to be initiated, to discussuplink data transmission in the inactive state. The intention of thesediscussions is to capture detail of the solution for sending uplink datawithout RRC signalling in the inactive state and without the UEinitiating a transition to the connected state. Focus should be on theRAN2 aspects and to be as independent as possible of the physical layermechanism that is used.

A first potential solution is discussed in 3GPP document R2-168544titled “UL data transmission in RRC_INACTIVE” (Huawei) [5]. Thissolution is shown in FIG. 3 , which is reproduced along with theaccompanying text from [5]. As shown in FIG. 3 , an uplink datatransmission 32 can be made by a network 30 in the RRC_INACTIVE state toan eNB 10. The network 30 here at least knows in which cell thetransmission 32 was received, and potentially may even know via whichTRP. For a certain amount of time after receiving an uplink data packet,the network 30 could assume that the UE 12 is still in the samelocation, so that any RLC acknowledgement or application response couldbe scheduled for transmission to the UE 12 in the same area where the UE12 is, for example in the next paging response 34. Alternatively, the UE12 may be paged in a wider area. Following reception of this downlinkresponse 34 the UE 12 may transmit an acknowledgement 36 to the network30 to indicate that it was successfully received.

A second potential solution is discussed in 3GPP document R2-168713titled “Baseline solution for small data transmission in RRC_INACTIVE”(Ericsson) [6]. This solution is shown in FIG. 4 , which is reproducedalong with the accompanying text from [6]. The mechanism described inFIG. 4 is for small data transmissions and is based on theSuspend-Resume mechanism for LTE. The main difference is that User Planedata is transmitted simultaneously with message 3 (the RRC Connectionresume request 44 in FIG. 4 ) and an optional RRC suspend signalled inmessage 4. As shown in FIG. 4 , initially under the assumption of arandom access scheme as in LTE, when a UE 12 receives uplink data totransmit to a gNB 10 of a mobile communications network, the UE 12 firsttransmits a random access (RA) preamble 40. Here a special set ofpreambles (a preamble partition) can be used as in LTE to indicate asmall data transmission (meaning that the UE 12 wants a larger grant andpossibly that the UE 12 wishes to remain in the inactive state).

The network responds with a random access response (RAR) message 42containing timing advance and a grant. The grant for message 3 should belarge enough to fit both the RRC request and a small amount of data. Theallowable size of the data could be specified and linked to thepreambles, e.g. preamble X asks for a grant to allow Y bytes of data.Depending on available resources, the gNB 10 may supply a grant formessage 3 accommodating only the resume request, in which case anadditional grant could be supplied after reception of message 3.

At this point the UE 12 will prepare the RRC Connection Resume Request44 and perform the following actions:

-   -   Re-establish Packet Data Convergence Protocol (PDCP) for SRBs        and all DRBs that are established;    -   Re-establish RLC for signalling radio bearers (SRBs) and all        data radio bearers (DRBs) that are established. The PDCP should        reset sequence numbers (SN) and hyper frame numbers (HFN) during        this step;    -   Resume SRBs and all DRBs that are suspended;    -   Derive a new security key (e.g. eNB key, or KeNB) possible based        on next-hop chaining counters (NCC) provided before the UE 12        was sent to the “inactive” state;    -   Generate encryption and integrity protection keys and configure        PDCP layers with previously configured security algorithm;    -   Generate RRC Connection Resume Request message 44;    -   An indication, e.g. a buffer status report (BSR), of potentially        remaining data is added;    -   An indication that the UE 12 wishes to remain in the inactive        state (if this is not indicated by the preamble) is added;    -   Apply the default physical channel and media access control        (MAC) configuration; and    -   Submit RRC Connection Resume Request 44 and data 46 to lower        layers for transmission.

After these steps, the lower layers transmit Message 3. This can alsocontain User Plane data 46 multiplexed by MAC, like existing LTEspecifications as security context is already activated to encrypt theUser Plane. The signalling (using SRB) and data (using DRB will bemultiplexed by MAC layer (meaning the data is not sent on the SRB).

The network 10 receives Message 3 and uses the context identifier toretrieve the UE's 12 RRC context and re-establish the PDCP and RLC forthe SRBs and DRBs. The RRC context contains the encryption key and theUser Plane data is decrypted (will be mapped to the DRB that isre-established or to an always available contention based channel).

Upon successful reception of Message 3 and User Plane data, the network10 responds with a new RRC response message 48 which could either be an“RRC suspend” or an “RRC resume” or an “RRC reject”. This transmissionresolves contention and acts as an acknowledgement of Message 3. Inaddition to RRC signalling the network 10 can in the same transmissionacknowledge any user data (RLC acknowledgements). Multiplexing of RRCsignalling and User Plane acknowledgements will be handled by the MAClayer. If the UE 12 loses the contention then a new attempt is needed.

-   -   In case the network 10 decides to resume the UE 12, the message        will be similar to a RRC resume and may include additional RRC        parameters.    -   In case the network 10 decides to immediately suspend the UE 12,        the message will be similar to a RRC suspend. This message can        possibly be delayed to allow downlink acknowledgements to be        transmitted.    -   In case the network 10 sends a resume reject the UE 12 will        initiate a new scheduling request (SR) as in LTE, after some        potential backoff time.

This procedure will, strictly speaking, transmit the User Plane datawithout the UE 12 fully entering RRC_CONNECTED, which formerly wouldhappen when the UE 12 receives the RRC Response (Message 4) indicatingresume. On the other hand, it uses the RRC context to enable encryptionetc. even if the network's decision is to make the UE 12 remain inRRC_INACTIVE by immediately suspending the UE 12 again.

FIGS. 5 and 6 each show examples of a simplified two-step RACHprocedure, in which small amounts of data can be transmitted by a UE 12to an gNB or eNB 12. In the two-step RACH procedure, the data istransmitted at the same time as the RACH preamble (message 62 in FIG. 6, and so there is no need for the UE 12 to wait for a response from thenetwork providing it with an uplink grant to transmit its data. However,the downside is that a limited amount of data can be transmitted inmessage 1. Following the reception of message 1 at the eNB 10, the eNB10 transmits a random access response (message 62 in FIG. 6 ) to the UE12, which comprises an acknowledgement of the received data in message1. FIG. shows the messages in a little more detail, where in message 1,the random access preamble 50, RRC connection resume request 52 and thesmall amount of data 54 are transmitted during the same transmissiontime interval (TTI). Likewise, for message 2, the random access responsewith timing advance 56 and the RRC response 58 (comprising anacknowledgement and RRC suspend command) are transmitted by the eNB 10to the UE 12 during the same TTI.

Embodiments of the present technique aim to provide a solution tooptimise the four step RACH, for example the LTE RACH procedure shown inFIG. 2 , and the two step RACH, such as that shown in FIGS. 5 and 6 , inorder to address medium to large data transmissions, where there is lessdelay and no requirement for communications devices to leave theinactive state.

Two-step RACH is expected to have advantages in reducing the datatransmission delay and signaling overhead. However, it is only designedfor small data transmissions. The reserved contention based resourcesfor carrying the data in RACH will not be very large. Then, using thetwo-step RACH solution, UEs which have large amounts of data to transmitmust adopt the conventional four-step LTE RACH procedure. Embodiments ofthe present technique provide solutions to accommodate large datatransmissions, while exploiting the advantages provided by theemployment of the two-step RACH design principle.

NR RACH Enhancement

Embodiments of the present technique provide systems and methods whichemploy a combined two-step and four-step RACH procedure to transmit datafrom a communications device, or UE, in an inactive state withoutnecessitating a transition to a connected state. Such systems andmethods comprise the containing of data in both message 1 and message 3,where message 1 comprises as much data as can be accommodated in thereserved contention based resources, as well as comprising an indicationto ask for an additional uplink grant. Message 3 comprises the remainderof the data to transmit, which will be done so using the additionaluplink grant requested in message 1. Message 2, which is the randomaccess response from the network, comprises the additional uplink grantas well as a unique identifier, such as a Cell Radio Network TemporaryIdentifier (C-RNTI) for the UE.

FIG. 7 provides a part schematic representation, part message flowdiagram of communications between a communications device or UE 12 and awireless communications network in accordance with embodiments of thepresent technique. The communications device 12 comprises a transmitter(or transmitter circuitry) 122 configured to transmit signals to one ormore infrastructure equipment or gNBs of the wireless communicationsnetwork via a wireless access interface 70 provided by the one or moreinfrastructure equipment 10, a receiver (or receiver circuitry) 124configured to receive signals from the one or more infrastructureequipment 10 via the wireless access interface 70, and a controller (orcontroller circuitry) 126 configured to control the transmittercircuitry 122 and the receiver circuitry 124 to transmit or to receivethe signals representing data. As can be seen in FIG. 7 , theinfrastructure equipment 10 also comprises a transmitter (or transmittercircuitry) 102 configured to transmit signals to the communicationsdevice 12 via the wireless access interface 70, a receiver (or receivercircuitry) 104 configured to receive signals from the communicationsdevice 12 via the wireless access interface 70, and a controller (orcontroller circuitry) 106 configured to control the transmittercircuitry 102 and the receiver circuitry 104 to transmit or to receivethe signals representing data. Each of the controllers 126, 106 may be,for example, a microprocessor, a CPU, or a dedicated chipset, etc.

When the communications device 12 is in an inactive state (which couldfor example correspond to the an idle state, such as the RRC_IDLEstate), the controller circuitry 126 of the communications device 12 isconfigured in combination with the receiver circuitry 124 and thetransmitter circuitry 122 of the communications device 12 to transmit afirst signal 72 comprising a random access preamble and a first portionof data to one of the infrastructure equipment 10, to receive a randomaccess response message 74 from the infrastructure equipment 10, and totransmit a second signal 76 comprising a second portion of the data tothe infrastructure equipment 10.

The preambles for the random access from the UE to gNB could be reservedin advance, e.g. in the system information of gNB. In such an instance,the gNB will broadcast the reserved preamble set for the random access,where this set differs from those used for the four-step RACH andtwo-step RACH procedures. In other words, this set of random accesspreambles are specifically used to indicate that a signal correspondingto the first signal is being transmitted—these preambles indicate thatthe new RACH procedure as defined by embodiments of the presenttechnique and is shown in FIG. 7 is occurring. As an alternative to thereserved preamble set being broadcast by the gNB, it will send dedicatedsignalling to UEs of the allocated preambles. As another alternative,the set of random access preambles may be set in the specifications, andknown to the UEs in advance.

The radio resources reserved for the transmission of data with thepreamble will be notified to UE via broadcast or dedicated signalling.In other words, the controller circuitry is configured in combinationwith the transmitter circuitry to transmit the first signal using firstradio resources indicated by the infrastructure equipment. As with theset of preambles, these could again be broadcast by the network,provided to the UE via dedicated signalling, or predefined in thespecifications and hence known to the UE in advance. These resources maybe different to those used for the transmission of preambles in thefour-step RACH procedure, and to those used for the transmissions ofpreambles and the small amount of data in the two-step RACH procedure.In addition to the radio resources reserved for the transmission ofdata, an allowed data size will also be notified to UE via broadcast ordedicated signalling.

In some embodiments of the present technique, there may be a linkagebetween preamble and resource e.g. with the preamble, the location ofthe resource blocks could be calculated. In that case, it isn'tnecessary to notify the UE of the reserved radio resources explicitly.In other words, the controller circuitry is configured in combinationwith the transmitter circuitry to determine first radio resources whichshould be used to transmit the first signal on the basis of the randomaccess preamble selected from the set of random access preambles, and totransmit the first signal using the determined radio resources. In termsof calculated resource blocks, the reserved resource blocks for the datapart of the transmitted first signal should have a longer guard period,because the UE has not received a timing advance (TA) command yet at thetime of the first transmission. In general, the preamble part is notrequired to frame timing alignment, but the data part in OFDM shouldfollow the TA command to avoid the conflict of receiving timing at thegNB from multiple users. In the embodiments described above, reservedresource blocks for the first transmission of the data part should haveenough guard periods to absorb propagation delay between the UE and thegNB without a TA command Preferably, a common predetermined guard periodand a predetermined transmission time unit (in other words, transmissiontime interval (TTI) for the data part of the first transmission) shouldbe used. This does not prevent there being multiple data sizes and TTIlengths, but a guard period should be inserted at suitable position andhave a suitable length. In order to calculate the location of theresource blocks, the assistance information may be sent with systeminformation, or may be defined within the 3GPP specifications (e.g.variables for calculation formula such as the required guard period, anallowable TTI length, frequency region and so on).

As the reserved radio resources for data transmission in RACH will notbe large, the data carried in message 1 would be only part of theoverall data that UE want to transmit, it may include, for example:

-   -   UE ID for contention resolution;    -   An indication to show there will be more data to transmit;    -   The data size to be transmitted;    -   RRC message, e.g. RRC connection resume request, RRC connection        setup request etc. in order to address large/continuous data        transmission; and    -   Part of user data which can be accommodated with reserved radio        resources.

In other words, the first signal further comprises one or more of afirst portion of user data, an identifier of the communications device,an indication that the second portion of data is available to betransmitted, an indication of the size of the second portion of data,and a Radio Resource Control, RRC, message comprising a request toresume an RRC connection or a request to set up a new RRC connection.

The channels used to transmit the random access preamble and the data ofmessage 1 could be different.

After receiving the preamble and data from the UE, the gNB will send arandom access response to the UE. The random access response mayinclude.

-   -   Detected preamble and UE ID: This field is to identify whether        the received random access response from gNB is for the UE who        sent the same random access preamble and UE ID;    -   Timing advance if necessary;    -   RRC reply if there is any RRC message sent in Msg 1 and ACK/NAK        for data;    -   UL grant. The gNB will allocate UL grant for additional data        transmission; and    -   A unique identifier, for example a C-RNTI. This identifier will        be used to address the following additional data transmission;

In other words, the random access response message comprises one or moreof an indication of an uplink grant, the uplink grant comprising secondradio resources which can be used by the communications device for thetransmission of the second signal, a unique identifier which is assignedby the infrastructure equipment to identify the communications devicefor the transmission of the second signal, an RRC response message inresponse to an RRC message comprised within the first signal, anindication of a random access preamble and/or communications deviceidentifier detected by the infrastructure equipment, an acknowledgementor negative acknowledgement, ACK/NACK, on the basis of whether the firstportion of the data was successfully received by the infrastructureequipment, and a timing advance command.

Message 3 may contain additional data to transmit, for example:

-   -   An RRC message if necessary following the RRC message sent in        message 2; and    -   User data which can not be fully accommodated in message 1.

In other words, as well as comprising the second portion of the data,the second signal further comprises a second RRC message in response tothe RRC response message received from the infrastructure equipment.

In some embodiments of the present technique, the controller isconfigured in combination with the receiver to receive an ACK/NACK onthe basis of whether the second portion of the data was successfullyreceived by the infrastructure equipment.

FIG. 8 shows a flow diagram illustrating a process of communicationsbetween a communications device operating in an inactive mode (e.g.RRC_IDLE) and an infrastructure equipment of a wireless communicationsnetwork in accordance with embodiments of the present technique. Themethod, which is a method of controlling the communications device,begins in step S1. The method comprises, in step S2, transmitting afirst signal via a wireless access interface provided by aninfrastructure equipment of the wireless communications network, thefirst signal comprising a random access preamble and a first portion ofdata to the infrastructure equipment. The method then comprises in stepS4, receiving a random access response message from the infrastructureequipment. In step S6, the process comprises transmitting a secondsignal comprising a second portion of the data to the infrastructureequipment. The process ends in step S8.

Advantages of embodiments of the present technique include a hybrid,enhanced RACH procedure which can be used in NR wireless communicationssystem which has both the advantage of the reduced delay performance ofthe presently known two-step RACH procedure, whilst large amounts ofdata can be accommodated with the data transmission with the RACH.

The following numbered paragraphs provide further example aspects andfeatures of the present technique:

Paragraph 1. A communications device for transmitting data to orreceiving data from a wireless communications network, thecommunications device comprising

-   -   transmitter circuitry configured to transmit signals to one or        more infrastructure equipment of the wireless communications        network via a wireless access interface provided by the one or        more infrastructure equipment,    -   receiver circuitry configured to receive signals from one or        more of the infrastructure equipment via the wireless access        interface, and    -   controller circuitry configured to control the transmitter        circuitry and the receiver circuitry to transmit or to receive        the signals representing data, wherein when the communications        device is in an inactive state, the controller circuitry is        configured in combination with the receiver circuitry and the        transmitter circuitry    -   to transmit a first signal comprising a random access preamble        and a first portion of data to one of the infrastructure        equipment,    -   to receive a random access response message from the        infrastructure equipment, and    -   to transmit a second signal comprising a second portion of the        data to the infrastructure equipment.

Paragraph 2. A communications device according to Paragraph 1, whereinthe controller circuitry is configured to select the random accesspreamble from a set of random access preambles which are specificallyused to indicate that a signal corresponding to the first signal isbeing transmitted.

Paragraph 3. A communications device according to Paragraph 1 orParagraph 2, wherein the controller circuitry is configured incombination with the transmitter circuitry to transmit the first signalusing first radio resources indicated by the infrastructure equipment.

Paragraph 4. A communications device according to Paragraph 2, whereinthe controller circuitry is configured in combination with thetransmitter circuitry

-   -   to determine first radio resources which should be used to        transmit the first signal on the basis of the random access        preamble selected from the set of random access preambles, and    -   to transmit the first signal using the determined radio        resources.

Paragraph 5. A communications device according to any of Paragraphs 1 to4, wherein the first signal further comprises one or more of:

-   -   a first portion of user data,    -   an identifier of the communications device,    -   an indication that the second portion of data is available to be        transmitted,    -   an indication of the size of the second portion of data, and    -   a Radio Resource Control, RRC, message comprising a request to        resume an RRC connection or a request to set up a new RRC        connection.

Paragraph 6. A communications device according to any of Paragraphs 1 to5, wherein the random access response message comprises one or more of:

-   -   an indication of an uplink grant, the uplink grant comprising        second radio resources which can be used by the communications        device for the transmission of the second signal,    -   a unique identifier which is assigned by the infrastructure        equipment to identify the communications device for the        transmission of the second signal,    -   an RRC response message in response to an RRC message comprised        within the first signal,    -   an indication of a random access preamble and/or communications        device identifier detected by the infrastructure equipment,    -   an acknowledgement or negative acknowledgement, ACK/NACK, on the        basis of whether the first portion of the data was successfully        received by the infrastructure equipment, and    -   a timing advance command.

Paragraph 7. A communications device according to Paragraph 6, whereinthe second signal further comprises a second RRC message in response tothe RRC response message received from the infrastructure equipment.

Paragraph 8. A communications device according to any of Paragraphs 1 to7, wherein the controller is configured in combination with the receiverto receive an ACK/NACK on the basis of whether the second portion of thedata was successfully received by the infrastructure equipment.

Paragraph 9. A method of operating a communications device in aninactive state for transmitting data to or receiving data from awireless communications network, the method comprising

-   -   transmitting a first signal via a wireless access interface        provided by an infrastructure equipment of the wireless        communications network, the first signal comprising a random        access preamble and a first portion of data to the        infrastructure equipment,    -   receiving a random access response message from the        infrastructure equipment, and    -   transmitting a second signal comprising a second portion of the        data to the infrastructure equipment.

Paragraph 10. A method according to Paragraph 9, wherein the firstsignal further comprises one or more of:

-   -   a first portion of user data,    -   an identifier of the communications device,    -   an indication that the second portion of data is available to be        transmitted,    -   an indication of the size of the second portion of data, and    -   a Radio Resource Control, RRC, message comprising a request to        resume an RRC connection or a request to set up a new RRC        connection.

Paragraph 11. A method according to Paragraph 9 or Paragraph 10, whereinthe random access response message comprises one or more of:

-   -   an indication of an uplink grant, the uplink grant comprising        second radio resources which can be used by the communications        device for the transmission of the second signal,    -   a unique identifier which is assigned by the infrastructure        equipment to identify the communications device for the        transmission of the second signal,    -   an RRC response message in response to an RRC message comprised        within the first signal,    -   an indication of a random access preamble and/or communications        device identifier detected by the infrastructure equipment,    -   an acknowledgement or negative acknowledgement, ACK/NACK, on the        basis of whether the first portion of the data was successfully        received by the infrastructure equipment, and    -   a timing advance command.

Paragraph 12. An infrastructure equipment for transmitting data to orreceiving data from a communications device, the infrastructureequipment forming part of a wireless communications network andcomprising

-   -   transmitter circuitry configured to transmit signals to the        communications device via a wireless access interface provided        by the wireless communications network,    -   receiver circuitry configured to receive signals from the        communications device via the wireless access interface, and    -   controller circuitry configured to control the transmitter        circuitry and the receiver circuitry to transmit or to receive        the signals representing data, wherein when the communications        device is in an inactive state, the controller circuitry is        configured in combination with the receiver circuitry and the        transmitter circuitry    -   to receive a first signal comprising a random access preamble        and a first portion of data from the communications device,    -   to transmit a random access response message to the        communications device, and    -   to receive a second signal comprising a second portion of the        data from the communications device.

Paragraph 13. A method of operating an infrastructure equipment fortransmitting data to or receiving data from a communications device inan inactive state, the infrastructure equipment forming part of awireless communications network, the method comprising

-   -   receiving a first signal via a wireless access interface        provided by the wireless communications network, the first        signal comprising a random access preamble and a first portion        of data from the communications device,    -   transmitting a random access response message to the        communications device, and    -   receiving a second signal comprising a second portion of the        data from the communications device.

Paragraph 14. Circuitry for a communications device for transmittingdata to or receiving data from a wireless communications network, thecommunications device comprising

-   -   transmitter circuitry configured to transmit signals to one or        more infrastructure equipment of the wireless communications        network via a wireless access interface provided by the one or        more infrastructure equipment,    -   receiver circuitry configured to receive signals from one or        more of the infrastructure equipment via the wireless access        interface, and    -   controller circuitry configured to control the transmitter        circuitry and the receiver circuitry to transmit or to receive        the signals representing data, wherein when the communications        device is in an inactive state, the controller circuitry is        configured in combination with the receiver circuitry and the        transmitter circuitry    -   to transmit a first signal comprising a random access preamble        and a first portion of data to one of the infrastructure        equipment,    -   to receive a random access response message from the        infrastructure equipment, and    -   to transmit a second signal comprising a second portion of the        data to the infrastructure equipment.

Paragraph 15. Circuitry for an infrastructure equipment for transmittingdata to or receiving data from a communications device, theinfrastructure equipment forming part of a wireless communicationsnetwork and comprising

-   -   transmitter circuitry configured to transmit signals to the        communications device via a wireless access interface provided        by the wireless communications network,    -   receiver circuitry configured to receive signals from the        communications device via the wireless access interface, and    -   controller circuitry configured to control the transmitter        circuitry and the receiver circuitry to transmit or to receive        the signals representing data, wherein when the communications        device is in an inactive state, the controller circuitry is        configured in combination with the receiver circuitry and the        transmitter circuitry    -   to receive a first signal comprising a random access preamble        and a first portion of data from the communications device,    -   to transmit a random access response message to the        communications device, and    -   to receive a second signal comprising a second portion of the        data from the communications device.

Numerous modifications and variations of the present disclosure arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the disclosuremay be practiced otherwise than as specifically described herein.

In so far as embodiments of the disclosure have been described as beingimplemented, at least in part, by software-controlled data processingapparatus, it will be appreciated that a non-transitory machine-readablemedium carrying such software, such as an optical disk, a magnetic disk,semiconductor memory or the like, is also considered to represent anembodiment of the present disclosure.

It will be appreciated that the above description for clarity hasdescribed embodiments with reference to different functional units,circuitry and/or processors. However, it will be apparent that anysuitable distribution of functionality between different functionalunits, circuitry and/or processors may be used without detracting fromthe embodiments.

Described embodiments may be implemented in any suitable form includinghardware, software, firmware or any combination of these. Describedembodiments may optionally be implemented at least partly as computersoftware running on one or more data processors and/or digital signalprocessors. The elements and components of any embodiment may bephysically, functionally and logically implemented in any suitable way.Indeed the functionality may be implemented in a single unit, in aplurality of units or as part of other functional units. As such, thedisclosed embodiments may be implemented in a single unit or may bephysically and functionally distributed between different units,circuitry and/or processors.

Although the present disclosure has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. Additionally, although a feature may appear to bedescribed in connection with particular embodiments, one skilled in theart would recognize that various features of the described embodimentsmay be combined in any manner suitable to implement the technique.

REFERENCES

-   [1] RP-151621, “New Work Item: NarrowBand IOT NB-IOT,” Qualcomm, RAN    #69.-   [2] RP-160671, “New SID Proposal: Study on New Radio Access    Technology,” NTT DOCOMO, RAN #71.-   [3] LTE for UMTS: OFDMA and SC-FDMA Based Radio Access, Harris Holma    and Antti Toskala, Wiley 2009, ISBN 978-0-470-99401-6.-   [4] ETSI TS 136 213 V13.0.0 (2016-01)/3GPP TS 36.212 version 13.0.0    Release 13.-   [5] R2-168544, “UL data transmission in RRC_INACTIVE,” Huawei,    HiSilicon, RAN #96.-   [6] R2-168713, “Baseline solution for small data transmission in    RRC_INACTIVE,” Ericsson, Ran #96.

What is claimed is:
 1. A communications device for transmitting data toor receiving data from wireless communications network, thecommunications device comprising transmitter circuitry configured totransmit signals to one or more infrastructure equipment of the wirelesscommunications network via a wireless access interface provided by theone or more infrastructure equipment, receiver circuitry configured toreceive signals from one or more of the infrastructure equipment via thewireless access interface, and controller circuitry configured tocontrol the transmitter circuitry and the receiver circuitry- totransmit or to receive the signals representing data, wherein when thecommunications device is in an inactive state, the controller circuitryis configured in combination with the receiver circuitry and thetransmitter circuitry to transmit a first signal comprising a randomaccess preamble and a first portion of data to one of the infrastructureequipment, to receive a random access response message from theinfrastructure equipment, and to transmit a second signal comprising asecond portion of the data to the infrastructure equipment.
 2. A methodof operating a communications device in an inactive state fortransmitting data to or receiving data from a wireless communicationsnetwork, the method comprising transmitting a first signal via awireless access interface provided by an infrastructure equipment of thewireless communications network, the first signal comprising a randomaccess preamble and a first portion of data to the infrastructureequipment, receiving a random access response message from theinfrastructure equipment, and transmitting a second signal comprising asecond portion of the data to the infrastructure equipment.
 3. A methodof operating an infrastructure equipment for transmitting data to orreceiving data from a communications device in an inactive state, theinfrastructure equipment forming part of a wireless communicationsnetwork, the method comprising receiving a first signal via a wirelessaccess interface provided by the wireless communications network, thefirst signal comprising a random access preamble and a first portion ofdata from the communications device, transmitting a random accessresponse message to the communications device, and receiving a secondsignal comprising a second portion of the data from the communicationsdevice.